Sheesh, why not do an empirical test & blow up the ECU
I am not concerned about theory and how incorrect Wikepedia is this time (its dodo's like me who write junk on there)
What I worry about is how it translates to practice !
& practice is not to ever run your Alternator without a buffer (Battery) connected to it
Your Alternator generates some interesting Voltages before it goes through the Bridge & then regulator.
I used to take the Voltage after the bridge & use the Alternator as a welding machine
So if you run it without a Battery to smooth things out, it could cause some interesting smoke